The trunked communication system is a specialized mobile communication system in which multiple users share and dynamically use one group of wireless channels. It is mainly applied in enterprises, security department, police, army etc., which have a high demand for commanding and dispatching functions. According to the technical schemes that are employed in the internal system, the trunked communication system can be divided into analog trunked communication system and digital trunked communication system. At present, the most widely used two types of TDMA (Time Division Multiple Access) digital trunked communication systems are iDEN (integrated Digital Enhanced Network) digital trunked communication system and terrestrial trunked Radio TETRA (Trans European Trunked Radio) communication system.
The above two types of trunked networks are both realized by using the second generation digital communication technology and the multi-address scheme of TDMA. However, with the ever mature third generation communication technology nowadays, TDMA scheme has such shortcomings as being unable of 3G smooth evolution, limited capacity, low success rate of switching and low data throughput, so it can not meet the ever increasing demands of communication.
CDMA system has broadband spread spectrum air interface, and it has successfully realized trunked service in CDMA2000 1x CDMA2000 HRPD (High Rate Packet Data) not only provides high speed packet data service, but also provides VOIP service. If combining the CDMA2000 HRPD technology and the trunked system together, it will not only exert the technical advantage of CDMA2000 HRPD, but also meet the user's demand of trunked service, such as trunked calling and group calling etc.
Within the time division wireless communication system, the common way of realizing trunking is to allocate fixed time slots to specialized groups. However, this technology has the following problem: when the number of the groups is increasing, the time delay problem will become more and more severe which will significantly affect the voice communication quality as well as the user's feeling; meanwhile, due to the limited data contents within each voice data packet, the fixed time slot distributed to each user will waste a large amount of bandwidths, as a result, other services can not be normally processed when more groups need to be supported.